This is mostly for the benefit of the First years who watched The Shining today. One of the things I like most about the film is that after every viewing a new interpretation arises. What struck me more than anything in the film on this particular occasion was the recurrence of pairs and the notion of 'duality' which is ever present throughout the film. Often, this is represented through mirrors which manifest as the physical representation of a splintering of reality and supernatural.
If you noticed, Jack and Danny's encounters with the The Overlook are almost always preceded by seeing visions in mirrors first. I think the mirror/duality theory of The Shining is perhaps the most sane interpretation because it's easily trackable within the film itself. It is both apparent as a means to understand the role of the characters and is observable in the design details of The Overlook.
Of course, I'm not the first person to ever make this observation and a quick Google search of 'The Shining and Mirrors' bought instant success. The first link is great because it makes reference to this idea directly in regards to the Production and Set design of the film. If anyone is struggling the make a clear connection of The Overlook as a representation of the characters of both Jack and Danny then these links should provide perfect fodder for your film reviews!